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The Vintage Japanese Motorcycle Owners Group: Discussion Forums

Vintage Japanese Motorcycle Owners Group :: View topic - Cold compression values, T20?


Cold compression values, T20?
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kbts250m
Weekend Warrior
Weekend Warrior


Joined: Jul 20, 2017
Posts: 91

PostPosted: Tue Nov 21, 2017 6:40 am    Post subject: Reply with quote

From your first post in this thread...
fodder wrote:

I did a compression test just now on the cold engine and got 70 psi on one and 75 on the other cylinder. I know it should be done hot, but I think even a cold engine should be higher than that. Can anybody comment? ......
I also dropped some oil in to the bores and got readings up to 80 - 85.


When you get the chance how about repeating that compression test? Nice way to close the loop!

I liked your infrared thermometer test and results. Snap-on Tools makes a diagnostic thermal imager ...
https://www.youtube.com/watch?v=Txp2S_e4g_Y ... and I thought it sure would be interesting to use one to check out air-cooled engines.

I feel the pain of winter too. Brrrrrrrr. At least you got your engine squared away before you have to put your bike in hibernation mode.

_________________
Currently - 75 Suz TS250, 02 Kaw ZX-6R

Previously - 70 Suz T350, 71 Suz TS250, 72 Suz GT380, 72 Suz TS125, 72 Suz TS250, 75 Yam YZ360B, 72 Suz GT380 diy cafe racer, 80 Suz GS750, 73 Suz TS185, 82 Suz GS1100
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fodder
Weekend Warrior
Weekend Warrior


Joined: Aug 28, 2017
Posts: 75
Location: Near Harlow, England

PostPosted: Tue Nov 21, 2017 2:44 pm    Post subject: Reply with quote

I was going to wait until the rings had bedded in a bit more but, since you ask so nicely, I have just nipped out to the garage. Result = 95 psi on both sides.

I suspect my gauge gives a low reading, as I have to use an extension tube to get the correct fitting and I think a long tube can decrease the reading.

That thermal imager looks neat but is a bit more expensive than my cheapo thermometer - getting on for $1,000 equivalent over here Shocked

A couple of pics below, from my files. One shows partway through rebuild, and the other me taking it on its first outing since it was laid up in 1972. These bikes really are little - I'm 5ft 9" but the bike looks small even for me! I was taking it for its MOT (roadworthiness test), which it passed first time.

These are before the engine work; note the smoke from the right pipe, it was burning gearbox oil. Thats what prompted the engine work. Luckily a bike of this age doesn't need an emissions test for the MOT but it wasn't very sociable when I rode it:oops:

The bike is now pretty well all overhauled:
- new wheel bearings
- new brake shoes
- new tyres and tubes
- new fork seals
- new front springs
- new steering head bearing races
- new chain and sprockets
- frame and swinging arm, plus stands blasted and powder coated.
- paintwork professionally resprayed
- new old stock speedo/tach
- saddle re-foamed and covered
- new wiring loom and battery
- new coils, condensers, points, plugs
- carbs overhauled with new jets and needles
- all new cables - brakes, throttle, oil pump.
- indicators installed (I managed to get a handlebar switch from a version that had these fitted)
- front brake light switch installed

Engine has had:
- all new seals
- refurbed crank - all bearings and seals
- new pistons and rebore
- replacement second gear to match the already installed later first gear.
- all new bearings in gearbox



First outing in 45 years.JPG
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First outing in 45 years.JPG



During rebuild.JPG
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During rebuild.JPG



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Nick
Suzuki T20 1965


Last edited by fodder on Thu Nov 23, 2017 4:51 am; edited 1 time in total
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kbts250m
Weekend Warrior
Weekend Warrior


Joined: Jul 20, 2017
Posts: 91

PostPosted: Wed Nov 22, 2017 6:18 am    Post subject: Reply with quote

Thanks for doing the compression test Fodder. That's a big improvement from your first posted results. Guaranteed that extension tube is causing a low reading. Both cylinders reading the same is indicative of a good rebuild and the greatly improved starting and power backs that up.

Thanks for the pic and details about everything you did. Your bike is AWESOME!!!! You should be proud of yourself.

So, are you done with your bike now or do you still have a few other refreshments in mind?

_________________
Currently - 75 Suz TS250, 02 Kaw ZX-6R

Previously - 70 Suz T350, 71 Suz TS250, 72 Suz GT380, 72 Suz TS125, 72 Suz TS250, 75 Yam YZ360B, 72 Suz GT380 diy cafe racer, 80 Suz GS750, 73 Suz TS185, 82 Suz GS1100
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spurlock
Commuter
Commuter


Joined: Jul 08, 2014
Posts: 884
Location: Vacaville, CA

PostPosted: Wed Nov 22, 2017 8:29 am    Post subject: Reply with quote

Fantastic job Nick, congratulations on your restoration. I'm sure you will enjoy many fun filled kilometers on it!

-Bill

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1975 Honda CB125S
1975 Honda XL250K2
1989 Honda NX250
1989 Honda GB500tt
1990 Honda GB500tt
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fodder
Weekend Warrior
Weekend Warrior


Joined: Aug 28, 2017
Posts: 75
Location: Near Harlow, England

PostPosted: Wed Nov 22, 2017 9:47 am    Post subject: Reply with quote

Thanks both of you for the kind comments. Its been a fun process. I had a T20 when I was a student, back in 1979 - 1981. It was not a bad bike but I maintained it on student money. So, for example, the link for the twin leading shoe brake became a slightly less than perfect link made from a wire coat hanger when the original broke. I had to do it as it was my only transport. You get the picture!

So now, when I can do things properly, it has been a relaxing and fulfilling process.

kbts, that is a good question! I can't sit still so there will be tweaks to be made. I will see how it goes, but I'm tempted by electronic ignition and a better electrical output so that I can put some bright daytime riding lights on it. Maybe something like this: Web Page Name

I'd be really interested to hear if anyone has any experience of this, or similar. Or maybe putting some LED daytime lights on with the original electrical set up?

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Nick
Suzuki T20 1965
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fodder
Weekend Warrior
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Joined: Aug 28, 2017
Posts: 75
Location: Near Harlow, England

PostPosted: Mon Nov 27, 2017 12:09 pm    Post subject: Reply with quote

I took a few pics at the weekend. The strange thing on the handlebars is a mobile phone holder. I put a speedo app on my phone so that I could check the bike speedo accuracy - its prettty accurate!


Nov 17.jpg
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Nick
Suzuki T20 1965
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kbts250m
Weekend Warrior
Weekend Warrior


Joined: Jul 20, 2017
Posts: 91

PostPosted: Wed Nov 29, 2017 5:39 am    Post subject: Reply with quote

Your bike is looking GREAT. I wish it was in my garage. Have you posted the original full-size pics on-line anywhere? I sure would like to see them. Have you been riding it much and how is it doing?
_________________
Currently - 75 Suz TS250, 02 Kaw ZX-6R

Previously - 70 Suz T350, 71 Suz TS250, 72 Suz GT380, 72 Suz TS125, 72 Suz TS250, 75 Yam YZ360B, 72 Suz GT380 diy cafe racer, 80 Suz GS750, 73 Suz TS185, 82 Suz GS1100
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fodder
Weekend Warrior
Weekend Warrior


Joined: Aug 28, 2017
Posts: 75
Location: Near Harlow, England

PostPosted: Thu Nov 30, 2017 10:15 am    Post subject: Reply with quote

Thanks!

Its getting a bit wintry and the roads are being salted so I won't be riding too much for a while. I did take it out on Sunday and put about 30 miles on it. It was running well so I was taking it to 5,000 rpm in the lower gears. I didn't push it too hard, or let it labour in higher gears.

I bought a couple of little but bright LED lights to fit as daytime riding lights. I need to work out where best to place them. Any ideas?

I'm not sure whether to wire them in to the first position on the ignition (no headlights on), so that they will be on whether I have the lights on or not, or to wire them in for the second position (headlights on). They are only 10 watts each so draw 0.8amps each.

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Suzuki T20 1965
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ConnerVT
Weekend Warrior
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Joined: Jun 01, 2012
Posts: 188
Location: North of Albany, NY, USA

PostPosted: Thu Nov 30, 2017 4:06 pm    Post subject: Reply with quote

20W is a significant draw for these old Suzukis. That is nearly the draw of the headlamp.

I don't know the wiring config of the T20, but it is likely similar to the later years, where the the headlight switches in additional coils of the alternator. Only one coil with the headlight switched off, three coils with it switched on. This was to keep from over-volting the battery, causing the electrolyte in the battery from boiling off.

In the stock configuration, even with the lighting switch on, I don't know if I would recommend adding more lighting.
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fodder
Weekend Warrior
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Location: Near Harlow, England

PostPosted: Sun Dec 03, 2017 7:41 am    Post subject: Reply with quote

Thanks for the reply. Yes, the T20 has that configuration, with one coil, then three coils, from position 1 to position 2.

You're right, the original headlight bulb is only 35/25watt so this would be a lot extra for the alternator.

I may have to investigate the aftermarket systems, then, although they are a bit pricy.

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Suzuki T20 1965
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ConnerVT
Weekend Warrior
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Posts: 188
Location: North of Albany, NY, USA

PostPosted: Sun Dec 03, 2017 8:44 am    Post subject: Reply with quote

I'm not at home, where all my resources are, so can't offer the details at the moment. But I can tell you what I did with my T500, to provide a bit more candlepower to improve the woefully inadequate lighting.

The old Suzukis (just like most bikes of that era) just don't have a lot of output from the alternator. Then, they were inefficient with how they handled the power that was generated. It was just how it was in 1960-1970's. Many of the smaller bikes didn't even have a voltage regulator, rather relying on the battery to do the job, and buffer the voltage swings generated by the charging circuit.

I ended up replacing the stock headlight with a patterned aftermarket headlight bucket, which uses a 45W halogen bulb. In order to handle the extra power demand, I did the following:

1. Replaced the stock rectifier and regulator with a solid state Tympanium rectifier/regulator. These are very popular with the vintage British bike folks. It is a bit more efficient, and keeps the output voltage more stable, so I could...

2. Replace the conventional lead acid battery with an AGM type battery. The glass mat batteries have a bit more capacity for their size, don't boil off like lead acid, and seem to also recover more quickly from a semi discharged state. They just aren't very tolerant of being overvolted, which is what happens if you just slap one in an old bike without upgrading the regulator.

3. Clean up *all* or the electrical connections. Every oxidized connector and marginal ground saps a little energy from the electrical system (Each is a small resistor. A death from 1000 paper cuts).

4. As I always run my headlight (day/night), I eliminated the alternator wiring to the headlight switch on the handlebars, directly wiring all three coils of the wiring to the rectifier/regulator. The wiring to the switch was needed to reduce the alternator output when the lights were off, to not boil off the battery electrolyte. As this is no longer an issue, you save a bit of current flow (more pesky connections!) lost from power needing to route up to the headlight switch and back.

I have been running this way for several years, and have never had an issue.
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fodder
Weekend Warrior
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Joined: Aug 28, 2017
Posts: 75
Location: Near Harlow, England

PostPosted: Sun Dec 03, 2017 10:44 am    Post subject: Reply with quote

That sounds like a good way to go for my bike too, thanks for the explanation.

The connectors are all new, I replaced them when I put the new loom in. So I think what I have is working as well as it can do but an upgrade would be handy.

One of the concerns I have is not so much being able to see where I'm going (although that is pretty useful Wink ) but being visible from the front if there is a modern car behind, with its xenon lights shining past and effectively masking the small beam from the bike.

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Suzuki T20 1965
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ConnerVT
Weekend Warrior
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Joined: Jun 01, 2012
Posts: 188
Location: North of Albany, NY, USA

PostPosted: Sun Dec 03, 2017 6:26 pm    Post subject: Reply with quote

Home now. I don't have T20 schematics, but imagine the T500 is similar enough for you to figure it out.

Original T500 wiring:



With solid state recifier/regulator:



The Green/White wire from the "Generator" can run straight to the Rec/Reg (disconnect/isolate the switch wiring first). Then will be running all 3 coils from the alternator 100% of the time. You will wish to always be running some lighting (be it your headlamp or the driving lights you wrote of). The extra energy generated needs to go somewhere, will be turned into heat at the regulator. Might as well use it for something useful, like lights.
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fodder
Weekend Warrior
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Joined: Aug 28, 2017
Posts: 75
Location: Near Harlow, England

PostPosted: Mon Dec 04, 2017 1:42 am    Post subject: Reply with quote

Thats great, thanks very much. I have the schematic for the T20 so will be able to work that together with these,.
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Nick
Suzuki T20 1965
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fodder
Weekend Warrior
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Joined: Aug 28, 2017
Posts: 75
Location: Near Harlow, England

PostPosted: Tue Dec 05, 2017 2:52 am    Post subject: Reply with quote

A couple of higher resolution shots of the bike.







I enquired about the Powerdynamo electronic ignition and uprated generator and received this reply:

"You get 80W (60/65W headlight, 10W taillight and a few indicator bulbs) only at about 1500 revs. Below this battery (so present) is discharged. Remember you also have stop lights, horn, flasher... The full 180W are available only at 4500 revs/min."
So it would be capable of running more than the current lighting but the guys at Powerdynamo are cautious about use of LEDs with their system. Powerdynamo

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Suzuki T20 1965
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